We assessed 110 left-handed and 322 right-handed children aged from 3 to 10 years, using Bishop's card-reaching task. Manual body midline crossings were observed. A regular developmental trend was observed from 3 to 10 years: older children crossed the body midline more frequently when reaching for cards than did younger children. The factor age explained 4.9% of the variance. Significant differences appeared between 3-4 years old children and 8-10 years old children. The effect of the spatial position of the cards was also significant: the contralateral hand was used less often to reach cards at the most extreme positions. These findings in this task demonstrate that the development of the degree of handedness follows a long developmental trend.